Abstract: A football helmet sizing card is described which permits convenient, rapid and efficient sizing and adjustment of football helmets on a football player's head. The card includes indicia which may be used to quickly and efficiently measure spacing of the football helmet from the player's eyebrows to the front rim of the helmet. The card is also sized in width so as to correspond to the manufacturer's recommended spacing distance from the nose to the face mask of the helmet. In this way, the card can be used quickly and efficiently over the course of the season to test for helmet sizing and adjustment, and this is particularly useful with helmets which have adjustable air bladder inflation systems so that appropriate inflation of the bladders can be made during the course of the season as atmospheric conditions warrant.